[rules-users] NPE for any @role( event )
I am using Drools version 5.4.0.Beta1. My rules are defined in a drl file.
I cannot get a type with @role(event) to run correctly. In every case I've
tried, I get the following error at runtime:
---------------------
java.lang.NullPointerException
at
org.drools.reteoo.ReteooFactHandleFactory.newFactHandle(ReteooFactHandleFactory.java:56)
at
org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:80)
at
org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:65)
at org.drools.common.NamedEntryPoint.createHandle(NamedEntryPoint.java:740)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:286)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:122)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:52)
at test.DroolsTest.main(DroolsTest.java:62)
--------------------
Looking at the source:
ReteooFactHandleFactory.java:56:
if ( type.getTimestampExtractor() != null ) {
"type" is null, hence the NPE. Tracing through in Eclipse, I find that in
ReteooFactHandleFactory.java, on line 54, is the following:
TypeDeclaration type = conf.getTypeDeclaration();
getTypeDeclaration() returns null. Stepped in, goes to
AbstractRuleBase.java:745:
public TypeDeclaration getTypeDeclaration( Class< ? > clazz ) {
TypeDeclaration typeDeclaration = this.classTypeDeclaration.get(
clazz );
if ( typeDeclaration == null ) {
// check super classes and keep a score of how up in the
hierarchy is there a declaration
TypeDeclarationCandidate candidate = checkSuperClasses( clazz );
// now check interfaces
candidate = checkInterfaces( clazz,
candidate,
1 );
if ( candidate != null ) {
typeDeclaration = candidate.candidate;
}
}
return typeDeclaration;
}
On line 746,
TypeDeclaration typeDeclaration = this.classTypeDeclaration.get( clazz );
this.classTypeDeclaration is type Map<Class< ? >, TypeDeclaration>. Map
is empty (size = 0), so the get() returns null. checkSuperClasses() and
checkInterfaces() also attempt to retrieve a TypeDeclaration from this same
(empty) map. So, a null typeDeclaration is returned.
Checking classTypeDeclaration references, the put() occurs in
AbstractRuleBase.addPackages() (AbstractRuleBase.java:476), and in
AbstractRuleBase.populateTypeDeclarationMaps() (AbstractRuleBase.java:336).
The latter is not called before the NPE. Execution in addPackages() do not
get to the classTypeDeclaration.put() because newPkg.getTypeDeclarations()
is empty. So, apparently, the TypeDeclaration is never put into the Map.
Attached is the minimal testcase that exhibits the same behavior.
http://drools.46999.n3.nabble.com/file/n3683063/TestRules.zip
TestRules.zip
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